The disclosure herein relates generally to electronic devices, and more particularly to digital camera modules. Even more particularly, it relates to a digital camera module manufacturing technique.
Digital camera modules are currently being incorporated into a variety of electronic devices. Such camera hosting devices include, but are not limited to, cellular telephones, personal digital assistants (PDAs), and computers. The demand for digital camera modules continues to grow as the ability to incorporate the camera modules into host devices expands. Therefore, one design goal of digital camera modules is to make them as small as possible so that they will fit into an electronic device without substantially increasing the overall size of the device. Means for achieving this goal must, of course, preserve the quality of the image captured by the camera modules.
Such digital camera modules typically include a substrate, an image capture device, a housing, and a lens unit. The substrate is typically a printed circuit board (PCB) that includes circuitry to facilitate data exchange between the image capture device and the host device. The image capture device is mounted and electrically coupled to the circuitry of the PCB. The housing is then mounted on the PCB over the image capture device. The housing includes an opening that receives and centers the lens unit with respect to the image capture device. The housing may include a voice coil motor (VCM) module for adjusting the position of the lens unit. To save time and costs of manufacturing, a group of camera modules may be simultaneously manufactured in array form.
The VCM module may include components such as a frame, permanent magnets, one or more springs, and an EMI shield. The magnets produce a strong magnetic field and will interact with another magnet nearby, such as if another VCM module is nearby. An example of this is shown in FIG. 1. This can present challenges in array manufacturing. Repelling forces from the magnets inside the VCM modules can cause inconsistent repelling distances, in one case in the range of 3.0-4.0 mm. Accordingly, larger spacing between image sensors on the silicon (minimum unit to unit gap 4.50 mm) may be required. This spacing increases the cost per camera module significantly. The EMI shield is designed to significantly block electromagnetic interference or flux, but does not significantly block magnetic flux.
One approach to addressing this problem is to increase the unit to unit gap. That is, increase the unit to unit gap to 4.50 mm in order to minimize the repelling force between the VCM. (Refer to panel layout in FIG. 2). One problem with this approach is that it results in inefficient and costly use of the silicon. Another problem is that the reduced unit quantity per silicon wafer results in a low VCM attach machine throughput (measured in units per hour, or UPH).
Another approach to addressing this problem includes the singulation method illustrated in FIG. 3. The image sensors on the silicon can be singulated and attached onto a copper frame with greater spacing than on the silicon. The singulation method is an additional process that increases the manufacturing cost. Also, the singulation method tends to generate particulate debris that can degrade the image quality of the camera module and cause high yield loss.
What is needed, therefore, is a camera module manufacturing technique that is allows for small module spacing in array processing.